Piperidine → HCID 178426287, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of 2,4-pentanedione (6.46 g, 64.6 mmol), 3-amino-5-mercapto-1,2,4-triazole (7.5 g, 64.6 mmol), glacial acetic acid (230 mL), and piperidine (0.58 mL, 5.9 mmol) was added to a 500 mL RBF with a magnetic stirring bar. The flask was fitted with a condenser, and warmed in an oil bath to a gentle reflux at 125° C. The mixture was heated for 45 hours, and solids remained visible in the flask throughout the heating period. Progress of the reaction was monitored by analytical HPLC with UV detection at 215 and 254 nm. The starting material 3-amino-5-mercapto-1,2,4-triazole elutes rapidly with retention time of 1.05 min, and the product elutes with retention time of 1.87 min. The mixture was cooled to room temperature. Solids were isolated by filtration, rinsed with 75 mL of acetic acid, and then dried under reduced pressure to afford the title compound as a pale yellow powder (9.5 g, 82% yield). A sample of 120 mg was recrystallized in warm acetic acid to afford 60 mg (50% recovery) of fine off-white needles, while the crude powder was used in the next step. 1H NMR (DMSO-d6+CDCl3, 400 MHz) δ ppm: 14.05 (br s, 1H), 7.25 (s, 1H), 2.67 (s, 3H), 2.56 (s, 3H). (NMR from crystalline material.)

Provenance & Evidence